Pest control hub

What does it look like?

Water hyacinth is a free-floating aquatic plant that can grow in dense mats. The leaves are glossy, green, leathery and up to 8cm across. The leaf stems are swollen and spongy and act like floats. Each plant has a mass of purple roots. It produces an attractive spike of up to ten large, lilac-mauve flowers, each with a yellow spot in the centre of one of the petals.

Water hyacinth grows in still or slow moving freshwater, such as ponds, streams, swamps and dams. In New Zealand, water hyacinth has been most common on small, nutrient-enriched waterbodies.

Why is it a problem?

Water hyacinth forms dense mats which can completely smother waterways and reduce water quality. The mats exclude native plants, block dams and waterways, impede drainage and disrupt recreational activities. Water hyacinth is frost-tender but the dense mats tolerate moderate frosts.

Water hyacinth reproduces from seeds which may remain viable for 20 years. It also reproduces vegetatively, young plants can grow from roots and can also produce seed within 3 to 4 weeks.

Eradication freshwater pests are pests that are present in low numbers or have a limited distribution within Northland and their eradication is thought to be feasible and cost-effective. These pests all have the potential to establish widely in the region, and are capable of causing adverse effects on the environmental, economic, social or cultural values of Northland. The council is either the lead agency or a partner for eradicating these pests from the region.

The NPPA is designed to prevent the sale, distribution and propagation of a set list of pest plants (the Accord list) within New Zealand. If allowed to spread further, these pest plants could seriously damage the New Zealand economy and environment.

An unwanted organism is any organism that's capable of causing harm to natural or physical resources (like forests and waterways) or human health. A number of introduced pests in New Zealand are classed as unwanted.

Under Section 52 and 53 of the Biosecurity Act 1993 no person can sell, propagate, breed, distribute or otherwise spread any pest in this Plan, or unwanted organism. Not complying with Section 52 or 53 is an offence under the Act, and may result in penalties noted Section 157(1).

Every person who sees, or suspects, the presence of any freshwater eradication pest shall immediately report the sighting to the Northland Regional Council

No person shall possess any freshwater eradication pest (including any seeds, live vegetation, eggs or juveniles) within Northland.

What is council doing about this?

If this plant is found the eradication will be done, free of charge by a NRC biosecurity officer or approved contractor.